Foamed Spacer Fluids Containing Cement Kiln Dust and Methods of Use

ABSTRACT

Disclosed are foamed spacer fluids comprising kiln dust for use in subterranean formations. An embodiment discloses a foamed spacer fluid comprising a partially calcined kiln feed removed from a gas stream comprising SiO2, Al2O3, Fe2O3, CaO, MgO, SO3, Na2O, and K2O; a foaming agent; a gas; and water.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.13/535,145, entitled “Foamed Spacer Fluids Containing Cement Kiln Dustand Methods of Use,” filed on Jun. 27, 2012, which is acontinuation-in-part of U.S. application Ser. No. 12/895,436, entitled“Spacer Fluids Containing Cement Kiln Dust and Methods of Use,” filed onSep. 30, 2010, which is a continuation-in-part of U.S. application Ser.No. 12/264,010, now U.S. Pat. No. 8,333,240, entitled “Reduced CarbonFootprint Sealing Compositions for Use in Subterranean Formations,”filed on Nov. 3, 2008, which is a continuation-in-part of U.S.application Ser. No. 11/223,669, now U.S. Pat. No. 7,445,669, entitled“Settable Compositions Comprising Cement Kiln Dust and Additive(s),”filed Sep. 9, 2005, the entire disclosures of which are incorporatedherein by reference.

BACKGROUND

The present invention relates to spacer fluids for use in subterraneanoperations and, more particularly, in certain embodiments, to foamedspacer fluids comprising cement kiln dust (“CKD”) and methods of use insubterranean formations.

Spacer fluids are often used in subterranean operations to facilitateimproved displacement efficiency when introducing new fluids into a wellbore. For example, a spacer fluid can be used to displace a fluid in awell bore before introduction of another fluid. When used for drillingfluid displacement, spacer fluids can enhance solids removal as well asseparate the drilling fluid from a physically incompatible fluid. Forinstance, in primary cementing operations, the spacer fluid may beplaced into the well bore to separate the cement composition from thedrilling fluid. Spacer fluids may also be placed between differentdrilling fluids during drilling change outs or between a drilling fluidand a completion brine, for example.

To be effective, the spacer fluid can have certain characteristics. Forexample, the spacer fluid may be compatible with the drilling fluid andthe cement composition. This compatibility may also be present atdownhole temperatures and pressures. In some instances, it is alsodesirable for the spacer fluid to leave surfaces in the well bore waterwet, thus facilitating bonding with the cement composition. Rheology ofthe spacer fluid can also be important. A number of differentrheological properties may be important in the design of a spacer fluid,including yield point, plastic viscosity, gel strength, and shearstress, among others. While rheology can be important in spacer fluiddesign, conventional spacer fluids may not have the desired rheology atdownhole temperatures. For instance, conventional spacer fluids mayexperience undesired theimal thinning at elevated temperatures. As aresult, conventional spacer fluids may not provide the desireddisplacement in some instances.

SUMMARY

The present invention relates to spacer fluids for use in subterraneanoperations and, more particularly, in certain embodiments, to foamedspacer fluids comprising CKD and methods of use in subterraneanformations.

An embodiment discloses a method comprising: providing a foamed spacerfluid comprising CKD, a foaming agent, a gas, and water; and introducingthe foamed spacer fluid into a well bore to displace at least a portionof a first fluid present in the well bore.

Another embodiment discloses a method comprising: providing a foamedspacer fluid comprising a partially calcined kiln feed removed from agas stream, a foaming agent, a gas, and water, wherein the partiallycalcined kiln feed comprises SiO₂, Al₂O₃, Fe₂O₃, CaO, MgO, SO₃, Na₂O,and K₂O; and introducing the foamed spacer fluid into a well bore todisplace at least a portion of a first fluid present in the well bore.

Yet another embodiment discloses a foamed spacer fluid comprising: CKD,a foaming agent, a gas, and water, wherein the foamed spacer fluid has:a higher yield point at 130° F. than at 80° F., a higher yield point at180° F. than at 80° F., and/or a higher plastic viscosity at 180° F.than at 80° F.

The features and advantages of the present invention will be readilyapparent to those skilled in the art. While numerous changes may be madeby those skilled in the art, such changes are within the spirit of theinvention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to spacer fluids for use in subterraneanoperations and, more particularly, in certain embodiments, to foamedspacer fluids that comprise CKD and methods that use CKD for enhancingone or more rheological properties of a spacer fluid. There may beseveral potential advantages to the methods and compositions of thepresent invention, only some of which may be alluded to herein. One ofthe many potential advantages of the methods and compositions of thepresent invention is that the CKD may be used in spacer fluids as arheology modifier allowing formulation of a spacer fluid with desirablerheological properties. Another potential advantage of the methods andcompositions of the present invention is that inclusion of the CKD inthe spacer fluids may result in a spacer fluid without undesired thermalthinning. Yet another potential advantage of the present invention isthat spacer fluids comprising CKD may be more economical thanconventional spacer fluids, which are commonly prepared with higher costadditives. Yet another potential advantage of the present invention isthat foamed spacer fluids comprising CKD may be used for displacement oflightweight drilling fluids.

Embodiments of the spacer fluids of the present invention may comprisewater and CKD. In some embodiments, the spacer fluids may be foamed. Forexample, the foamed spacer fluids may comprise water, CKD, a foamingagent, and a gas. A foamed spacer fluid may be used, for example, whereit is desired for the spacer fluid to be lightweight. In accordance withpresent embodiments, the spacer fluid may be used to displace a firstfluid from a well bore with the spacer fluid having a higher yield pointthan the first fluid. For example, the spacer fluid may be used todisplace at least a portion of a drilling fluid from the well bore.Other optional additives may also be included in embodiments of thespacer fluids as desired for a particular application. For example, thespacer fluids may further comprise viscosifying agents, organicpolymers, dispersants, surfactants, weighting agents, and anycombination thereof.

The spacer fluids generally should have a density suitable for aparticular application as desired by those of ordinary skill in the art,with the benefit of this disclosure. In some embodiments, the spacerfluids may have a density in the range of from about 4 pounds per gallon(“lb/gal”) to about 24 lb/gal. In other embodiments, the spacer fluidsmay have a density in the range of about 4 lb/gal to about 17 lb/gal. Inyet other embodiments, the spacer fluids may have a density in the rangeof about 8 lb/gal to about 13 lb/gal. Embodiments of the spacer fluidsmay be foamed or unfoamed or comprise other means to reduce theirdensities known in the art, such as lightweight additives. Those ofordinary skill in the art, with the benefit of this disclosure, willrecognize the appropriate density for a particular application.

The water used in an embodiment of the spacer fluids may include, forexample, freshwater, saltwater (e.g., water containing one or more saltsdissolved therein), brine (e.g., saturated saltwater produced fromsubterranean formations), seawater, or any combination thereof.Generally, the water may be from any source, provided that the waterdoes not contain an excess of compounds that may undesirably affectother components in the spacer fluid. The water is included in an amountsufficient to form a pumpable spacer fluid. In some embodiments, thewater may be included in the spacer fluids in an amount in the range offrom about 15% to about 95% by weight of the spacer fluid. In otherembodiments, the water may be included in the spacer fluids of thepresent invention in an amount in the range of from about 25% to about85% by weight of the spacer fluid. One of ordinary skill in the art,with the benefit of this disclosure, will recognize the appropriateamount of water to include for a chosen application.

The CKD may be included in embodiments of the spacer fluids as arheology modifier. Among other things, using CKD in embodiments of thepresent invention can provide spacer fluids having rheology suitable fora particular application. Desirable rheology may be advantageous toprovide a spacer fluid that is effective for drilling fluiddisplacement, for example. In some instances, the CKD can be used to,provide a spacer fluid with a low degree of thermal thinning. Forexample, the spacer fluid may even have a yield point that increases atelevated temperatures such as those encountered downhole.

CKD is a material generated during the manufacture of cement that iscommonly referred to as cement kiln dust. The term “CKD” is used hereinto mean cement kiln dust as described herein and equivalent forms ofcement kiln dust made in other ways. The term “CKD” typically refers toa partially calcined kiln feed which can be removed from the gas streamand collected, for example, in a dust collector during the manufactureof cement. Usually, large quantities of CKD are collected in theproduction of cement that are commonly disposed of as waste. Disposal ofthe waste CKD can add undesirable costs to the manufacture of thecement, as well as the environmental concerns associated with itsdisposal. Because the CKD is commonly disposed as a waste material,spacer fluids prepared with CKD may be more economical than conventionalspacer fluids, which are commonly prepared with higher cost additives.The chemical analysis of CKD from various cement manufactures variesdepending on a number of factors, including the particular kiln feed,the efficiencies of the cement production operation, and the associateddust collection systems. CKD generally may comprise a variety of oxides,such as SiO₂, Al₂O₃, Fe₂O₃, CaO, MgO, SO₃, Na₂O, and K₂O.

The CKD may be included in the spacer fluids in an amount sufficient toprovide, for example, the desired rheological properties. In someembodiments, the CKD may be present in the spacer fluids in an amount inthe range of from about 1% to about 65% by weight of the spacer fluid(e.g., about 1%, about 5%, about 10%, about 15%, about 20%, about 25%,about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about60%, about 65%, etc.). In some embodiments, the CKD may be present inthe spacer fluids in an amount in the range of from about 5% to about60% by weight of the spacer fluid. In some embodiments, the CKD may bepresent in an amount in the range of from about 20% to about 35% byweight of the spacer fluid. Alternatively, the amount of CKD may beexpressed by weight of dry solids. As used herein, the term “by weightdry solids” refers to the amount of a component, such as CKD, relativeto the overall amount of dry solids used in preparation of the spacerfluid. For example, the CKD may be present in an amount in a range offrom about 1% to 100% by weight of dry solids (e.g., about 1%, about 5%,about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about70%, about 80%, about 90%, 100%, etc.). In some embodiments, the CKD maybe present in an amount in the range of from about 50% to 100% and,alternatively, from about 80% to 100% by weight of dry solids. One ofordinary skill in the art, with the benefit of this disclosure, willrecognize the appropriate amount of CKD to include for a chosenapplication.

While the preceding description describes CKD, the present invention isbroad enough to encompass the use of other partially calcined kilnfeeds. For example, embodiments of the spacer fluids may comprise limekiln dust, which is a material that is generated during the manufactureof lime. The term lime kiln dust typically refers to a partiallycalcined kiln feed which can be removed from the gas stream andcollected, for example, in a dust collector during the manufacture oflime. The chemical analysis of lime kiln dust from various limemanufactures varies depending on a number of factors, including theparticular limestone or dolomitic limestone feed, the type of kiln, themode of operation of the kiln, the efficiencies of the lime productionoperation, and the associated dust collection systems. Lime kiln dustgenerally may comprise varying amounts of free lime and free magnesium,lime stone, and/or dolomitic limestone and a variety of oxides, such asSiO₂, Al₂O₃, Fe₂O₃, CaO, MgO, SO₃, Na₂O, and K₂O, and other components,such as chlorides.

Optionally, embodiments of the spacer fluids may further comprise flyash. A variety of fly ashes may be suitable, including fly ashclassified as Class C or Class F fly ash according to American PetroleumInstitute, API Specification for Materials and Testing for Well Cements,API Specification 10, Fifth Ed., Jul. 1, 1990. Suitable examples of flyash include, but are not limited to, POZMIX® A cement additive,commercially available from Halliburton Energy Services, Inc., Duncan,Okla. Where used, the fly ash generally may be included in the spacerfluids in an amount desired for a particular application. In someembodiments, the fly ash may be present in the spacer fluids in anamount in the range of from about 1% to about 60% by weight of thespacer fluid (e.g., about 5%, about 10%, about 15%, about 20%, about25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%,etc.). In some embodiments, the fly ash may be present in the spacerfluids in an amount in the range of from about 1% to about 35% by weightof the spacer fluid. In some embodiments, the fly ash may be present inthe spacer fluids in an amount in the range of from about 1% to about10% by weight of the spacer fluid. Alternatively, the amount of fly ashmay be expressed by weight of dry solids. For example, the fly ash maybe present in an amount in a range of from about 1% to about 99% byweight of dry solids (e.g., about 1%, about 5%, about 10%, about 20%,about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about90%, about 99%, etc.). In some embodiments, the fly ash may be presentin an amount in the range of from about 1% to about 20% and,alternatively, from about 1% to about 10% by weight of dry solids. Oneof ordinary skill in the art, with the benefit of this disclosure, willrecognize the appropriate amount of the fly ash to include for a chosenapplication.

Optionally, embodiments of the spacer fluids may further comprise a freewater control additive. As used herein, the term “free water controladditive” refers to an additive included in a liquid for, among otherthings, reducing (or preventing) the presence of free water in theliquid. Free water control additive may also reduce (or prevent) thesettling of solids. Examples of suitable free water control additivesinclude, but are not limited to, bentonite, amorphous silica,hydroxyethyl cellulose, and combinations thereof. An example of asuitable free water control additive is SA-1015™ suspending agent,available from Halliburton Energy Services, Inc. Another example of asuitable free water control additive is WG-17™ solid additive, availablefrom Halliburton Energy Services, Inc. The free water control additivemay be provided as a dry solid in some embodiments. Where used, the freewater control additive may be present in an amount in the range of fromabout 0.1% to about 16% by weight of dry solids, for example. Inalternative embodiments, the free water control additive may be presentin an amount in the range of from about 0.1% to about 2% by weight ofdry solids.

In some embodiments, the spacer fluids may further comprise alightweight additive. The lightweight additive may be included to reducethe density of embodiments of the spacer fluids. For example, thelightweight additive may be used to form a lightweight spacer fluid, forexample, having a density of less than about 13 lb/gal. The lightweightadditive typically may have a specific gravity of less than about 2.0.Examples of suitable lightweight additives may include sodium silicate,hollow microspheres, gilsonite, perlite, and combinations thereof. Anexample of a suitable sodium silicate is ECONOLITE™ additive, availablefrom Halliburton Energy Services, Inc. Where used, the lightweightadditive may be present in an amount in the range of from about 0.1% toabout 20% by weight of dry solids, for example. In alternativeembodiments, the lightweight additive may be present in an amount in therange of from about 1% to about 10% by weight of dry solids.

As previously mentioned, embodiments of the spacer fluids may be foamedwith a gas, for example, to provide a spacer fluid with a reduceddensity. It should be understood that reduced densities may be neededfor embodiments of the spacer fluids to more approximately match thedensity of a particular drilling fluid, for example, where lightweightdrilling fluids are being used. A drilling fluid may be consideredlightweight if it has a density of less than about 13 lb/gal,alternatively, less than about 10 lb/gal, and alternatively less thanabout 9 lb/gal. In some embodiments, the spacer fluids may be foamed tohave a density within about 10% of the density of the drilling fluidand, alternatively, within about 5% of the density of the drillingfluid. While techniques, such as lightweight additives, may be used toreduce the density of the spacer fluids comprising CKD without foaming,these techniques may have drawbacks. For example, reduction of thespacer fluid's density to below about 13 lb/gal using lightweightadditives may produce unstable slurries, which can have problems withsettling of solids, floating of lightweight additives, and free water,among others. Accordingly, the spacer fluid may be foamed to provide aspacer fluid having a reduced density that is more stable.

Therefore, in some embodiments, the spacer fluids may be foamed andcomprise water, CKD, a foaming agent, and a gas. Optionally, to providea spacer fluid with a lower density and more stable foam, the foamedspacer fluid may further comprise a lightweight additive, for example.With the lightweight additive, a base slurry may be prepared that maythen be foamed to provide an even lower density. In some embodiments,the foamed spacer fluid may have a density in the range of from about 4lb/gal to about 13 lb/gal and, alternatively, about 7 lb/gal to about 9lb/gal. In one particular embodiment, a base slurry may be foamed from adensity of in the range of from about 9 lb/gal to about 13 lb/gal to alower density, for example, in a range of from about 7 lb/gal to about 9lb/gal.

The gas used in embodiments of the foamed spacer fluids may be anysuitable gas for foaming the spacer fluid, including, but not limited toair, nitrogen, and combinations thereof. Generally, the gas should bepresent in embodiments of the foamed spacer fluids in an amountsufficient to form the desired foam. In certain embodiments, the gas maybe present in an amount in the range of from about 5% to about 80% byvolume of the foamed spacer fluid at atmospheric pressure,alternatively, about 5% to about 55% by volume, and, alternatively,about 15% to about 30% by volume.

Where foamed, embodiments of the spacer fluids may comprise a foamingagent for providing a suitable foam. As used herein, the term “foamingagent” refers to a material or combination of materials that facilitatethe formation of a foam in a liquid. Any suitable foaming agent forforming a foam in an aqueous liquid may be used in embodiments of thespacer fluids. Examples of suitable foaming agents may include, but arenot limited to: mixtures of an ammonium salt of an alkyl ether sulfate,a cocoamidopropyl betaine surfactant, a cocoamidopropyl dimethylamineoxide surfactant, sodium chloride, and water; mixtures of an ammoniumsalt of an alkyl ether sulfate surfactant, a cocoamidopropylhydroxysultaine surfactant, a cocoamidopropyl dimethylamine oxidesurfactant, sodium chloride, and water; hydrolyzed keratin; mixtures ofan ethoxylated alcohol ether sulfate surfactant, an alkyl or alkeneamidopropyl betaine surfactant, and an alkyl or alkene dimethylamineoxide surfactant; aqueous solutions of an alpha-olefinic sulfonatesurfactant and a betaine surfactant; and combinations thereof. Anexample of a suitable foaming agent is FOAMER™ 760 foamer/stabilizer,available from Halliburton Energy Services, Inc. Suitable foaming agentsare described in U.S. Pat. Nos. 6,797,054, 6,547,871, 6,367,550,6,063,738, and 5,897,699, the entire disclosures of which areincorporated herein by reference.

Generally, the foaming agent may be present in embodiments of the foamedspacer fluids in an amount sufficient to provide a suitable foam. Insome embodiments, the foaming agent may be present in an amount in therange of from about 0.8% to about 5% by volume of the water (“bvow”).

A wide variety of additional additives may be included in the spacerfluids as deemed appropriate by one skilled in the art, with the benefitof this disclosure. Examples of such additives include, but are notlimited to, weighting agents, viscosifying agents (e.g., clays,hydratable polymers, guar gum), fluid loss control additives, lostcirculation materials, filtration control additives, dispersants,defoamers, corrosion inhibitors, scale inhibitors, formationconditioning agents. Specific examples of these, and other, additivesinclude organic polymers, surfactants, crystalline silica, amorphoussilica, fumed silica, salts, fibers, hydratable clays, microspheres,rice husk ash, combinations thereof, and the like. A person havingordinary skill in the art, with the benefit of this disclosure, willreadily be able to determine the type and amount of additive useful fora particular application and desired result.

Embodiments of the spacer fluids of the present invention may beprepared in accordance with any suitable technique. In some embodiments,the desired quantity of water may be introduced into a mixer (e.g., acement blender) followed by the dry blend. The dry blend may comprisethe CKD and additional solid additives, for example. Additional liquidadditives, if any may be added to the water ac desired prior to orafter, combination with the dry blend. This mixture may be agitated fora sufficient period of time to form a base slurry. This base slurry maythen be introduced into the well bore via pumps, for example. In thefoamed embodiments, the base slurry may be pumped into the well bore,and a foaming agent may be metered into the base slurry followed byinjection of a gas, e.g., at a foam mixing “T,” in an amount sufficientto foam the base slurry thereby forming a foamed spacer fluid, inaccordance with embodiments of the present invention. After foaming, thefoamed spacer fluid may be introduced into a well bore. As will beappreciated by those of ordinary skill in the art, with the benefit ofthis disclosure, other suitable techniques for preparing spacer fluidsmay be used in accordance with embodiments of the present invention.

An example method of the present invention includes a method ofenhancing rheological properties of a spacer fluid. The method maycomprise including CKD in a spacer fluid. The CKD may be included in thespacer fluid in an amount sufficient to provide a higher yield pointthan a first fluid. The higher yield point may be desirable, forexample, to effectively displace the first fluid from the well bore. Asused herein, the term “yield point” refers to the resistance of a fluidto initial flow, or representing the stress required to start fluidmovement. In an embodiment, the yield point of the spacer fluid at atemperature of up to about 180° F. is greater than about 5 lb/100 ft².In an embodiment, the yield point of the spacer fluid at a temperatureof up to about 180° F. is greater than about 10 lb/100 ft². In anembodiment, the yield point of the spacer fluid at a temperature of upto about 180° F. is greater than about 20 lb/100 ft². It may bedesirable for the spacer fluid to not thermally thin to a yield pointbelow the first fluid at elevated temperatures. Accordingly, the spacerfluid may have a higher yield point than the first fluid at elevatedtemperatures, such as 180° F. or bottom hole static temperature(“BHST”). In one embodiment, the spacer fluid may have a yield pointthat increases at elevated temperatures. For example, the spacer fluidmay have a yield point that is higher at 180° F. than at 80° F. By wayof further example. The spacer fluid may have a yield point that ishigher at BHST than at 80° F.

Another example method of the present invention includes a method ofdisplacing a first fluid from a well bore, the well bore penetrating asubterranean formation. The method may comprise providing a spacer fluidthat comprises CKD and water. The method may further compriseintroducing the spacer fluid into the well bore to displace at least aportion of the first fluid from the well bore. In some embodiments, thespacer fluid may be characterized by having a higher yield point thanthe first fluid at 80° F. In some embodiments, the spacer fluid may becharacterized by having a higher yield point than the first fluid at130° F. In some embodiments, the spacer fluid may be characterized byhaving a higher yield point than the first fluid at 180° F.

In an embodiment, the first fluid displaced by the spacer fluidcomprises a drilling fluid. By way of example, the spacer fluid may beused to displace the drilling fluid from the well bore. The drillingfluid may include, for example, any number of fluids, such as solidsuspensions, mixtures, and emulsions. Additional steps in embodiments ofthe method may comprise introducing a pipe string into the well bore,introducing a cement composition into the well bore with the spacerfluid separating the cement composition and the first fluid. In anembodiment, the cement composition may be allowed to set in the wellbore. The cement composition may include, for example, cement and water.

Another example method of the present invention includes a method ofseparating fluids in a well bore, the well bore penetrating asubterranean formation. The method may comprise introducing a spacerfluid into the well bore, the well bore having a first fluid disposedtherein. The spacer fluid may comprise, for example, CKD and water. Themethod may further comprise introducing a second fluid into the wellbore with the spacer fluid separating the first fluid and the secondfluid. In an embodiment, the first fluid comprises a drilling fluid andthe second fluid comprises a cement composition. By way of example, thespacer fluid may prevent the cement composition from contacting thedrilling fluid. In an embodiment, the cement composition comprisescement kiln dust, water, and optionally a hydraulic cementitiousmaterial. A variety of hydraulic cements may be utilized in accordancewith the present invention, including, but not limited to, thosecomprising calcium, aluminum, silicon, oxygen, iron, and/or sulfur,which set and harden by reaction with water. Suitable hydraulic cementsinclude, but are not limited to, Portland cements, pozzolana cements,gypsum cements, high alumina content cements, slag cements, silicacements, and combinations thereof. In certain embodiments, the hydrauliccement may comprise a Portland cement. In some embodiments, the Portlandcements that are suited for use in the present invention are classifiedas Classes A, C, H, and G cements according to American PetroleumInstitute, API Specification for Materials and Testing for Well Cements,API Specification 10, Fifth Ed., Jul. 1, 1990. The spacer fluid may alsoremove the drilling fluid, dehydrated/gelled drilling fluid, and/orfilter cake solids from the well bore in advance of the cementcomposition Removal of these compositions from the well bore may enhancebonding of the cement composition to surfaces in the well bore. In anadditional embodiment, at least a portion of used and/or unused CKDcontaining spacer fluid are included in the cement composition that isplaced into the well and allowed to set.

To facilitate a better understanding of the present invention, thefollowing examples of certain aspects of some embodiments are given. Inno way should the following examples be read to limit, or define, thescope of the invention. In the following examples, concentrations aregiven in weight percent of the overall composition.

Example 1

Sample spacer fluids were prepared to evaluate the rheologicalproperties of spacer fluids containing CKD. The sample spacer fluidswere prepared as follows. First, all dry components (e.g., CKD, fly ash,bentonite, FWCA, etc.) were weighed into a glass container having aclean lid and agitated by hand until blended. Tap water was then weighedinto a Waring blender jar. The dry components were then mixed into thewater with 4,000 rpm stirring. The blender speed was then increased to12,000 rpm for about 35 seconds.

Sample Spacer Fluid No. 1 was an 11 pound per gallon slurry thatcomprised 60.62% water, 34.17% CKD, 4.63% fly ash, and 0.58% free watercontrol additive (WG-17™ solid additive).

Sample Spacer Fluid No. 2 was an 11 pound per gallon slurry thatcomprised 60.79% water, 30.42% CKD, 4.13% fly ash, 0.17% free watercontrol additive (WG-17™ solid additive), 3.45% bentonite, and 1.04%Econolite™ additive.

Rheological values were then determined using a Fann Model 35Viscometer. Dial readings were recorded at speeds of 3, 6, 100, 200, and300 with a B1 bob, an R1 rotor, and a 1.0 spring. The dial readings,plastic viscosity, and yield points for the spacer fluids were measuredin accordance with API Recommended Practices 10B, Bingham plastic modeland are set forth in the table below. The abbreviation “PV” refers toplastic viscosity, while the abbreviation “YP” refers to yield point.

TABLE 1 Sample Temp. Viscometer RPM PV YP Fluid (° F.) 300 200 100 6 3(cP) (lb/100 ft²⁾ 1 80 145 127 90 24 14 113.3 27.4 180 168 143 105 26 15154.5 30.3 2 80 65 53 43 27 22 41.1 26.9 180 70 61 55 22 18 51.6 25.8

The thickening time of the Sample Spacer Fluid No. 1 was also determinedin accordance with API Recommended Practice 10B at 205° F. Sample SpacerFluid No. 1 had a thickening time of more than 6:00+ hours at 35 Bc.

Accordingly, the above example illustrates that the addition of CKD to aspacer fluid may provide suitable properties for use in subterraneanapplications. In particular, the above example illustrates, inter alia,that CKD may be used to provide a spacer fluid that may not exhibitthermal thinning with the spacer fluid potentially even having a yieldpoint that increases with temperature. For example, Sample Spacer FluidNo. 2 had a higher yield point at 180° F. than at 80° F. In addition,the yield point of Sample Spacer Fluid No. 1 had only a slight decreaseat 180° F. as compared to 80° F. Even further, the example illustratesthat addition of CKD to a spacer fluid may provide a plastic viscositythat increases with temperature.

Example 2

Additional sample spacer fluids were prepared to further evaluate therheological properties of spacer fluids containing CKD. The samplespacer fluids were prepared as follows. First, all dry components (e.g.,CKD, fly ash) were weighed into a glass container having a clean lid andagitated by hand until blended. Tap water was then weighed into a Waringblender jar. The dry components were then mixed into the water with4,000 rpm stirring. The blender speed was then increased to 12,000 rpmfor about 35 seconds.

Sample Fluid No. 3 was a 12.5 pound per gallon fluid that comprised47.29% water and 52.71% CKD.

Sample Fluid No. 4 was a 12.5 pound per gallon fluid that comprised46.47% water, 40.15% CKD, and 13.38% fly ash.

Sample Fluid No. 5 was a 12.5 pound per gallon fluid that comprised45.62% water, 27.19% CKD, and 27.19% fly ash.

Sample Fluid No. 6 was a 12.5 pound per gallon fluid that comprised44.75% water, 13.81% CKD, and 41.44% fly ash.

Sample Fluid No. 7 (comparative) was a 12.5 pound per gallon fluid thatcomprised 43.85% water, and 56.15% fly ash.

Rheological values were then determined using a Fann Model 35Viscometer. Dial readings were recorded at speeds of 3, 6, 30, 60, 100,200, 300, and 600 with a B1 bob, an R1 rotor, and a 1.0 spring. The dialreadings, plastic viscosity, and yield points for the spacer fluids weremeasured in accordance with API Recommended Practices 10B, Binghamplastic model and are set forth in the table below. The abbreviation“PV” refers to plastic viscosity, while the abbreviation “YP” refers toyield point.

TABLE 2 CKD- Sample Fly YP Spacer Ash Temp. Viscometer RPM PV (lb/ FluidRatio (° F.) 600 300 200 100 60 30 6 3 (cP) 100 ft²⁾ 3 100:0  80 33 2320 15 13 12 8 6 12 11 130 39 31 27 23 22 19 16 11 12 19 180 66 58 51 4740 38 21 18 16.5 41.5 4 75:25 80 28 22 19 15 14 11 8 6 10.5 11.5 130 3928 25 21 19 16 14 11 10.5 17.5 180 51 39 36 35 31 26 16 11 6 33 5 50:5080 20 11 8 6 5 4 4 3 7.5 3.5 130 21 15 13 10 9 8 6 5 7.5 7.5 180 25 2017 14 13 12 7 5 9 11 6 25:75 80 16 8 6 3 2 1 0 0 7.5 0.5 130 15 8 6 4 32 1 1 6 2 180 15 9 7 5 4 4 2 2 6 3 7  0:100 80 16 7 5 3 1 0 0 0 6 1(Comp.) 130 11 4 3 1 0 0 0 0 4.5 −0.5 180 8 3 2 0 0 0 0 0 4.5 −1.5

Accordingly, the above example illustrates that the addition of CKD to aspacer fluid may provide suitable properties for use in subterraneanapplications. In particular, the above example illustrates, inter alia,that CKD may be used to provide a spacer fluid that may not exhibitthermal thinning with the spacer fluid potentially even having a yieldpoint that increases with temperature. In addition, as illustrated inTable 2 above, higher yield points were observed for spacer fluids withhigher concentrations of CKD.

Example 3

A sample spacer fluid containing CKD was prepared to compare therheological properties of a spacer fluid containing CKD with anoil-based drilling fluid. The sample spacer fluid was prepared asfollows. First, all dry components (e.g., CKD, fly ash, bentonite, etc.)were weighed into a glass container having a clean lid and agitated byhand until blended. Tap water was then weighed into a Waring blenderjar. The dry components were then mixed into the water with 4,000 rpmstirring. The blender speed was then increased to 12,000 rpm for about35 seconds.

Sample Spacer Fluid No. 8 was an 11 pound per gallon slurry thatcomprised 60.79% water, 30.42% CKD, 4.13% fly ash, 0.17% free watercontrol additive (WG-17™ solid additive), 3.45% bentonite, and 1.04%Econolite™ additive.

The oil-based drilling fluid was a 9.1 pound per gallon oil-based mud.

Rheological values were then determined using a Fann Model 35Viscometer. Dial readings were recorded at speeds of 3, 6, 100, 200, and300 with a B1 bob, an R1 rotor, and a 1.0 spring. The dial readings,plastic viscosity, and yield points for the spacer fluid and drillingfluid were measured in accordance with API Recommended Practices 10B,Bingham plastic model and are set forth in the table below. Theabbreviation “PV” refers to plastic viscosity, while the abbreviation“YP” refers to yield point. The abbreviation “OBM” refers to oil-basedmud.

TABLE 3 Sample Temp. Viscometer RPM PV YP Fluid (° F.) 300 200 100 6 3(cP) (lb/100 ft²⁾ 8 80 59 50 39 22 15 42 21.2 180 82 54 48 16 13 65.3 17OBM 80 83 64 41 11 10 74.6 12.1 180 46 35 23 10 10 36.7 10.5

Accordingly, the above example illustrates that the addition of CKD to aspacer fluid may provide suitable properties for use in subterraneanapplications. In particular, the above example illustrates, inter alia,that CKD may be used to provide a spacer fluid with a yield point thatis greater than a drilling fluid even at elevated temperatures. Forexample, Sample Spacer Fluid No. 8 has a higher yield point at 180° F.than the oil-based mud.

Example 4

A foamed spacer fluid was prepared that comprised CKD. First, a baseslurry was prepared that had a density of 10 lb/gal and comprised CKD, afree water control additive (0.7% by weight of CKD), a lightweightadditive (4% by weight of CKD), and fresh water (32.16 gallons per94-pound sack of CKD). The free water control additive was SA-1015™suspending aid. The lightweight additive was ECONOLITE™ additive. Next,a foaming agent (FOAMER™ 760 foamer/stabilizer) in an amount of 2% bvowwas added, and the base slurry was then mixed in a foam blending jar for4 seconds at 12,000 rpm. The resulting foamed spacer fluid had a densityof 8.4 lb/gal. The “sink” of the resultant foamed spacer fluid was thenmeasured using a free fluid test procedure as specified in APIRecommended Practice 10B. However, rather than measuring the free fluid,the amount of “sink” was measured after the foamed spacer fluid remainedstatic for a period of 2 hours. The foamed spacer fluid was initially at200° and cooled to ambient temperature over the 2-hour period. Themeasured sink for this foamed spacer fluid was 5 millimeters.

Example 5

Another foamed spacer fluid was prepared that comprised CKD. First, abase slurry was prepared that had a density of 10.5 lb/gal and comprisedCKD, a free water control additive (0.6% by weight of CKD), alightweight additive (4% by weight of CKD), and fresh water (23.7gallons per 94-pound sack of CKD). The free water control additive wasSA-1015™ suspending aid. The lightweight additive was ECONOLITE™additive. Next, a foaming agent (a hexylene glycol/cocobetaine blendedsurfactant) in an amount of 2% bvow was added, and the base slurry wasthen mixed in a foam blending jar for 6 seconds at 12,000 rpm. Theresulting foamed spacer fluid had a density of 8.304 lb/gal. Theresultant foamed spacer fluid had a sink of 0 millimeters, measured asdescribed above for Example 4.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein.Although individual embodiments are discussed, the invention covers allcombinations of all those embodiments. The particular embodimentsdisclosed above are illustrative only, as the present invention may bemodified and practiced in different but equivalent manners apparent tothose skilled in the art having the benefit of the teachings herein.Furthermore, no limitations are intended to the details of constructionor design herein shown, other than as described in the claims below. Itis therefore evident that the particular illustrative embodimentsdisclosed above may be altered or modified and all such variations areconsidered within the scope and spirit of the present invention. Whilecompositions and methods are described in terms of “comprising,”“containing,” or “including” various components or steps, thecompositions and methods can also “consist essentially of” or “consistof” the various components and steps. Whenever a numerical range with alower limit and an upper limit is disclosed, any number and any includedrange falling within the range is specifically disclosed. In particular,every range of values (of the form, “from about a to about b,” or,equivalently, “from approximately a to b,” or, equivalently, “fromapproximately a-b”) disclosed herein is to be understood to set forthevery number and range encompassed within the broader range of values.Also, the terms in the claims have their plain, ordinary meaning unlessotherwise explicitly and clearly defined by the patentee.

What is claimed is:
 1. A foamed spacer fluid for displacing at least aportion of a first fluid present in a well bore comprising: a partiallycalcined kiln feed removed from a gas stream comprising SiO₂, Al₂O₃,Fe₂O₃, CaO, MgO, SO₃, Na₂O, and K₂O; a foaming agent; a gas; and water.2. The foamed spacer fluid of claim 1, wherein the foamed spacer fluidhas a yield point at 80° F. that is higher than a yield point of thefirst fluid at 80° F.
 3. The foamed spacer fluid of claim 1, wherein thefoamed spacer fluid has a yield point at 180° F. that is higher than ayield point of the first fluid at 180° F.
 4. The foamed spacer fluid ofclaim 1, wherein the foamed spacer fluid has a higher yield point atbottom hole static temperature of the well bore than at 80° F.
 5. Thefoamed spacer fluid of claim 1, wherein the yield point of the foamedspacer fluid at 180° F. is greater than about 20 lb/100 ft².
 6. Thefoamed spacer fluid of claim 1, wherein the foamed spacer fluid has adensity in the range of from about 4 lb/gal to about 13 lb/gal.
 7. Thefoamed spacer fluid of claim 1, wherein the partially calcined kiln feedis present in the foamed spacer fluid in an amount in a range of fromabout 1% to about 65% by weight of the foamed spacer fluid.
 8. Thefoamed spacer fluid of claim 1, wherein the gas comprises at least onegas selected from the group consisting of air, nitrogen, and anycombination thereof; and wherein the foaming agent comprises at leastone additive selected from the group consisting of a mixture of anammonium salt of an alkyl ether sulfate, a cocoamidopropyl betainesurfactant, a cocoamidopropyl dimethylamine oxide surfactant, sodiumchloride, and water; a mixture of an ammonium salt of an alkyl ethersulfate surfactant, a cocoamidopropyl hydroxysultaine surfactant, acocoamidopropyl dimethylamine oxide surfactant, sodium chloride, andwater; hydrolyzed keratin; a mixture of an ethoxylated alcohol ethersulfate surfactant, an alkyl or alkene amidopropyl betaine surfactant,and an alkyl or alkene dimethylamine oxide surfactant; an aqueoussolution of an alpha-olefinic sulfonate surfactant and a betainesurfactant; and any combination thereof.
 9. The foamed spacer fluid ofclaim 1, wherein the partially calcined kiln feed is present in thefoamed spacer fluid in an amount in a range of from about 80% to 100% byweight of dry solids.
 10. The foamed spacer fluid of claim 1, whereinthe first fluid comprises a drilling fluid.
 11. The foamed spacer fluidof claim 1, wherein a second fluid is present in the well bore and thefoamed spacer fluid separates the first fluid from the second fluid. 12.The foamed spacer fluid of claim 11, wherein the second fluid is acement composition.
 13. The foamed spacer fluid of claim 1, wherein thepartially calcined kiln feed is from the manufacture of cement.
 14. Thefoamed spacer fluid of claim 1, wherein the partially calcined kiln feedis from the manufacture of lime.
 15. The foamed spacer fluid of claim 1,wherein the foamed spacer fluid further comprises at least one additiveselected from the group consisting of a free water control additive, alightweight additive, a weighting agent, a viscosifying agent, a fluidloss control additive, a lost circulation material, a filtration controladditive, a dispersant, a corrosion inhibitor, a scale inhibitor, aformation conditioning agent, and any combination thereof.
 16. Thefoamed spacer fluid of claim 1, wherein the foamed spacer fluid furthercomprises at least one additive selected from the group consisting offly ash, a clay, a hydratable polymer, guar gum, an organic polymer, asurfactant, crystalline silica, amorphous silica, fumed silica, a salt,a fiber, hydratable clay, a microsphere, rice husk ash, and anycombination thereof.
 17. The foamed spacer fluid of claim 1, wherein thefoamed spacer fluid has: (a) a higher yield point at 130° F. than at 80°F., (b) a higher yield point at 180° F. than at 80° F., and/or (c) ahigher plastic viscosity at 180° F. than at 80° F.
 18. A foamed spacerfluid for displacing at least a portion of a first fluid present in awell bore comprising: cement kiln dust; a foaming agent; a gas; andwater, wherein the foamed spacer fluid has a density in a range of fromabout 4 lb/gal to about 13 lb/gal.
 19. The foamed spacer fluid of claim18, wherein a second fluid is present in the well bore and the foamedspacer fluid separates the first fluid from the second fluid.
 20. Afoamed spacer fluid comprising: cement kiln dust; a foaming agent; agas; and water, wherein the foamed spacer fluid has: (a) a higher yieldpoint at 130° F. than at 80° F., (b) a higher yield point at 180° F.than at 80° F., and/or (c) a higher plastic viscosity at 180° F. than at80° F.